Pre-implantation Genetic Diagnosis (PGD)

The PGD Procedure

Pre-implantation genetic diagnosis (PGD) is a technology that allows analysis of the genetic make-up of the early embryo before it is transferred into the uterus. PGD is similar to other invasive prenatal screening tests, except it is done at a much earlier stage than common diagnostic procedures such as chorionic villus sampling (CVS) and amniocentesis. Namely, it is done prior to implantation of the early embryo, whereas CVS and amniocentesis are performed well after implantation had occurred.

Similar to CVS and amniocentesis, PGD is able to detect three basic genetic characteristics in the embryo:

1. Chromosomal aneuploidy - an abnormal number of chromosomes (e.g. Down’s Syndrome, Trisomy 13, Trisomy 18, Turner’s Syndrome…)
2. Single gene defects - specific genetic mutations leading to known diseases (e.g. Cystic fibrosis, Tay-Sachs, Thalassemia…)
3. Gender (male or female)

In order for PGD to be performed, couples must undergo IVF with or without ICSI to allow for the formation of early embryos in the laboratory. When embryos are three days old (typically containing 7-8 cells), PGD is performed by inserting a tiny needle into each embryo and removing 1 or 2 cells (called blastomeres). Various techniques of gene amplification and chromosomal analysis are next applied in order to analyze removed blastomeres for their genetic make-up. Embryos determined to be abnormal, or of the wrong gender (in the case of sex linked genetic diseases, or for sex selection purposes), are discarded. Normal embryos are transferred into the uterus within 24 hours of the procedure. Numerous animal and human studies have documented the safety of PGD and its benefits in assuring that a healthy embryo is chosen for transfer.

Who are candidates for PGD?

1. Couples who are known carriers of specific genetic mutations or who have previously had a genetically affected child have a significantly increased risk of having a genetically affected offspring.
    
2. Couples who are known carriers of a chromosomal aberration such as a translocation have a significantly increased risk of recurrent pregnancy loss and implantation failures.
    
3. Women of advanced reproductive age and couples who have had recurrent pregnancy loss due to chromosomal aneuploidy.
    
4. Couples who have several children of one gender and are interested in sex selection/family balancing.

CFG is proud to offer all PGD services in our state of the art laboratory.